This invention relates to the incorporation of electronic sorting equipment in a field tomato harvester.
Electronic sorting machines have been placed on the market commercially. These electronic sorters operate on the basis of color. When tomatoes are ripe, their skin color is a good tomato red. Green tomatoes are obviously unripe, and tomatoes that are still yellow or have not reached a certain degree and intensity of redness, are unripe. The electronic sorter is able to distinguish between these various colors of tomatoes by causing light of a certain spectrum range to be reflected off them and back into the electronic sorter. The electronic sorter is provided with swinging fingers that are able to engage unripe tomatoes and deflect them from a normal path that ripe tomatoes follow. These machines have been perfected to the extent that each finger can make as many as ten decisions a second and act on those decisions, so that they can handle large quantities of tomatoes.
The basic problem to which this invention is directed is the adaptation of such an electronic sorter to tomato harvesters.
A typical tomato harvester has some sort of pickup means for severing and picking up the tomato plants from a field, elevating means for raising them to a desired height, and separating means for detaching the tomatoes from the plants and then placing them in a different stream from the remainder of the plant material. This is probably best accomplished by a shaking apparatus of well-known type. Once the tomatoes have been separated, they, along with as little extraneous material as possible, are usually routed by suitable cross-conveyors at the rear of the harvester, into forwardly travelling sorting conveyors, usually one on each side of the harvester. Alongside these are platforms which heretofore have had to support a number of workers, up to a dozen on each side, all of them performing a hand-sorting operation, judging the ripeness of the tomatoes by color and also noting whether they are spoiled or damaged. These sorters have discarded the culls. The sorted tomatoes which were not discarded have heretofore fallen off the forward end of the sorting conveyor on to a suitable front cross-conveyor which moved them into a takeoff conveyor where they were loaded into truck trailers, usually moving along the field parallel to the tomato harvester.
Electronic sorters are very attractive, because hand sorting is expensive while it requires only a low degree of skill. It is boring and yet demanding work, and the cost of employing so many people is so great that many tomato growers believe that an expensive electronic sorting device will enable them to save money and even to pay for the devices in the first year they use it. This does not mean that hand sorting can be entirely dispensed with, as will be seen, but it does mean that it can be reduced to a very low level.
Thus, it is desirable to provide a suitable structure by which tomato harvesters can be adapted to electronic sorting. Several problems are related to this adaptation. One of the problems is that the electronic sorter requires that the tomatoes it is sorting be moving in a substantially constant type of trajectory; in other words, that all the tomatoes drop off the forward edge of a conveyor at the same speed and fall toward a desired end point by a path from which it is to be deflected only if rejected. This is somewhat difficult to achieve because tomatoes are round and tend to roll; moreover, there has been a comparatively small amount of space in which to squeeze such an electronic sorting operation without very expensive modification of the machine construction and without creating other disadvantages, such as awkward locations for the electronic sorters.
Another problem brought about by electronic sorting is that since the tomatoes are to be sorted by color, it is important for the tomatoes to come from a conveyor which will not introduce false values that reduce the accuracy of the sorting. This means that the conveyor forms a background reflecting or not reflecting the light which is projected on the tomatoes. If the belt is the wrong color or if it changes color, there may be rejections where there should be acceptances and therefore a reduction in the crop harvested, tomatoes which should not be culled out, being culled out.
The heights and lateral or longitudinal distances available on a tomato harvester are such that the adaptation of the harvester to electronic sorting involves relatively short distances within which a number of functions have to be performed.